This application relates generally to mechanical connectors, and more particularly to connectors that absorb vibration.
An elastic bushing may be an integral part of an upper damper bearing or spring strut support bearing of a motor vehicle. The non-deflected state of the elastic bushing is the defined middle position in the state of static equilibrium, taking into account the gas force of the shock absorber or any other constant pre-load.
The following is a discussion of relevant art pertaining to elastic bushings. The discussion is provided only for understanding of the invention that follows. The summary is not an admission that any of the work described below is prior art to the claimed invention.
A European patent EP 0816140 B1 relates to a spring strut support bearing for wheel suspensions in a motor vehicle. The spring strut support bearing includes a vertically pot-shaped metallic housing; a rubber buffer arranged in the housing; a carrying piece, connectable to a damper, fixed to the rubber buffer through radially extending projections; an annular spring buffer supporting the upper end of a helical spring surrounding the damper; a radially directed housing flange forming a stay for the spring buffer; a cover plate, fastenable to a motor vehicle component, covering the rubber buffer and connected to the housing flange; and a one-piece metallic collar margin located on the underside of the housing and guides the damper radially. The housing is caulked with the cover plate. Recesses with a geometry changing in the circumferential direction, independently of the load, are provided in regions on the spring buffer side, which is supported by the housing flange.
Another German patent DE 19932868A1 discloses a spring strut including a spring plate, cooperating with one end of a piston rod, being arranged to be cardanically movable with respect to the piston rod. An elastic element provides this arrangement between the spring plate and the piston rod. For the upper spring strut support bearing, which may also be designated as a damper bushing, non-linearly progressive stiffness properties are required in the axial direction. On one hand, low stiffness is required in the event of a small deflection in order to improve the noise behavior (NVH=Noise Vibration Harshness). On the other hand, high stiffness is needed in case of a large deflection such that the damper forces can be absorbed without an excessive deflection occurring in the elastic bushing or in the damper bushing. It should be apparent that a balance between low and high stiffness should be achieved. Non-linear stiffness provides not only comfortable but agile driving and steering properties of a motor vehicle.
As used in this specification, the term “cardan joint,” and its derivative modifiers “cardanic” and “cardanically,” signify a joint that permits motion in any direction. The most widely-used example of such a joint to use referred to as a “universal joint,” having two rotational axes close to one another, the axes oriented at 90° to one another. Universal joints are generally found on a rod or tube-like structure, such as the drive shaft of an automobile, providing the rod into two sections which may lie at any angle to one another. In the general case, cardanic joints simply permit movement in any direction.
Therefore, it would be highly desirable to have an improved damper bushing that increases driving comfort and eliminates the sensitivity of the bushing towards angular deflections.